Around the idea of Alan's modular platform, I have devised some chordal Big Sixes which, in combination with some kind of melodic (e.g. blues scale) Big Six, would constitute a highly adaptable system.

The diagrams below show five different chordal Big Sixes. I also show five tables, each of which describes how these harps can be combined with melodic Big Sixes in corresponding keys.

The table below incorporates the "alternative note pattern" described in the post just above this one.

It also specifies the lowest possible tunings for Big Sixes, according to Seydel's Configurator at this time. Of course, if one used these six chambers as merely the beginning of a 10-, 12- or 13-hole harp, even lower chords are possible.

The two tunings above, identified as "Cmaj" for the first one and "Emaj" for the second one, make up two parts of a functional triad of tunings that are equally spaced (by four semitones) on the Circle of Fifths. The third tuning of this triad is shown below.

There are four possible triads of this nature. Their relationships are laid out below.